The New Worlds Misson aims to discover and analyze terrestrial extrasolar planets.

The New Worlds concept features two, or more efficiently, three, spacecraft flying at the Earth-Sun L2 (Lagrangian) point or in a drift-away solar orbit (orbit options are under study). One craft carries a 4-meter aperture-diameter diffraction-limited telescope optimized to work in the visible band (extension into the near-ultraviolet and near-infrared is likely). The other “occulter” craft would each carry a starshade. Operating 70,000 kilometers from the telescope, one starshade would be maneuvered into the telescope’s line-of-sight to a nearby star, blocking starlight while passing planet light. Each starshade can project a very deep shadow wherein the telescope operates.

The starshade produces a shadow, the center of which is extremely dark over the entire spectral band from 0.4 to 1.1 micrometers, accommodating the telescope with margin for alignment control. The starshades will need to be about 50 meters tip-to-tip and may be made of any dark, opaque, deployable material.

Because of the large distance between the telescope and the occulter, slewing between stellar targets presents a challenge for this mission. The occulter must physically move thousands of kilometers to occupy its next line-of-sight. Moving slowly to conserve fuel, this can take up to two weeks. While New Worlds requires only one occulter to function, its overall efficiency is greatly enhanced by a second occulter that can travel while the other is in use. As the occulters are low in cost compared to the telescope, this is a highly cost-efficient upgrade.

We estimate that with two starshades, observing efficiency can be near 50%. Thus there will be large amounts of time available for general astrophysics (such as dark-energy studies). For other astrophysics the starshades are capable of, click here. Also, simultaneous long-exposure observations of planets and wide field-of-view surrounding their position will generate many deep-field images useful for cosmology.

The sensitivity to terrestrial planets rises very quickly with aperture because higher resolution leads to greater suppression of the exozodiacal light beneath the planet signal. The telescope must be diffraction-limited at 0.5 micrometers, with angular resolution less than 0.03”. This resolution is achieved by a 3.5-meter (or larger) aperture.